Tiet Q.Q., Leyva Y.E., Moos R.H. et al.
JAMA Internal Medicine: 2015, 175(8), p. 1371–1377.
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Just two simple questions (and often just one) correctly identified around 9 in 10 patients with drug use problems among a US primary care sample.
Summary Primary care provides an ideal setting in which to screen not just for risky drinking, but also for drug use disorders and negative consequences of drug use. However, screening questionnaires and interviews intended to quickly signal whether these problems are present have been found by comprehensive reviews to be inappropriate for routine use in primary care.
1. “How many days in the past 12 months have you used drugs other than alcohol?”
If 7 or more days, the SoDU is positive for drug use disorder and negative consequences; skip item 2.
2. “How many days in the past 12 months have you used drugs more than you meant to?”
If 2 or more days then SoDU is positive for drug use disorder and negative consequences.
This US study set out to develop and validate a screening instrument for drug use suitable for primary care settings. Items from existing instruments were tested on 1283 adult patients (of 3173 initially approached for the study) at two primary care clinics run by the US Department of Veterans Affairs health care system for ex-military personnel. Patients were almost all men and averaged 62 years of age. In interviews with researchers, 19% of participants reported in the last 12 months having used illicit drugs or prescription medications for non-medical purposes, and 15% reported at least one negative consequence of this use. Just over 1 in 10 met criteria for a drug use disorder (abuse or dependence) according to the US diagnostic system.
The sample was randomly divided in two. The first half were used to test candidate items drawn from existing screening instruments in order to develop the new instrument, the second half to validate the new instrument. In each case the assessments made by the screening questions were benchmarked against more comprehensive assessments made by using already validated questionnaires.
The resulting screening instrument had two questions, the second only needing to be asked if the response to the first had not been indicative of a drug use disorder or negative consequences panel above. Among the second half of the sample used to validate the instrument, it correctly identified 92% of the patients diagnosed by a more comprehensive assessment as having a drug use disorder, and correctly did not indicate a disorder for 93% of patients also found disorder-free by the more comprehensive tests. For negative consequences of drug use the corresponding proportions were 83% and 97%. When the Screen of Drug Use was re-answered by 100 patients a week later the results remained almost the same, indicating that the results are stable over time. Accuracy was maintained for subgroups of the sample divided by age, sex, racial or ethnic background, marital status, educational level, and whether suffering post-traumatic stress disorder.
The analysts concluded that SoDU two-item screening instrument for drug use has excellent accuracy and reliability, and provides a way to briefly screen for drug use disorders and problems suitable for busy US Department of Veterans Affairs primary care clinics. However, the sample was mainly elderly men and the instrument may not work as well in other types of primary care populations.
commentary It is important to remember that in this study patients were responding in confidence to researchers in a context in which their answers could have no bearing on their medical care, relationships with medical staff, or other aspects of their lives. Patients may be more reluctant to admit to frequent illegal drug use or misuse of medications to their doctors. Only a validation study in which the screening instrument is tested in conditions approximating normal practice can tell whether in these conditions it also accurately identifies problem drug use. This may be particularly important outside the context of the US military health service where deference to military authority and associated traditions and training may result in more truthful responses to sensitive questions than in other contexts.
Thanks for their comments on this entry in draft to Mick McManus, Alcohol Co-ordinator at the London Borough of Barking and Dagenham in England. Commentators bear no responsibility for the text including the interpretations and any remaining errors.
Last revised 16 October 2015. First uploaded 09 October 2015
STUDY 2012 A randomized controlled trial of a brief intervention for illicit drugs linked to the Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) in clients recruited from primary health-care settings in four countries